It is known in the field of surface coating and particularly vinyl surface coverings to provide a non-woven fibrous substrate to receive the resinous wear-like layer. The fibrous support layer usually consists of either an organic fiber felt such as cellulose or polypropylene fiber or a mineral fiber felt such as asbestos fiber or glass fiber or a mixture of both and the felt is impregnated with a synthetic resin saturant or binder such as a synthetic rubber or latex.
Initially, the incorporation of 1-5% of asbestos fibers was made to improve the dimensional stability of the cellulose felt. Subsequently, it was found that the incorporation of higher levels of from 10 to 50% of asbestos markedly improved the dimensional stability of the felts over those incorporating only from 1-5%.
Other non-woven fibrous base felt material have been prepared by binding a mixture of cellulosic fibers and an inert inorganic filler or charge such as magnesium hydroxide, calcium carbonate, titanium oxide, talc, mica, clay, alumina, perlite and similar inert fillers. The selection of the filler or charge is based on its cost and its compatibility with the other ingredients used in the compounding of the non-woven fibrous base felt material.
As suggested by the above list, almost any inorganic insoluble material can be used. However, the performances are not the same with all the inorganic fillers, some giving more interesting behaviors than others depending on many factors such as the polarity of the surface, the specific surface, the hydrophillic or hydrophobic character and the like.
It is obvious that a filler that would incorporate fibers would be very advantageous since it would contribute to the overall strength of the end product.
The recovery of asbestos fiber from asbestos containing rocks is accompanied by the production of substantial amounts of finely divided rock, mostly serpentine (magnesium silicate: 3MgO.2SiO.sub.2.2H.sub.2 O) which are rejected in the course of the extraction of the fiber and is designated as tailings or residues. This serpentine incorporates a variable amount of chrysotile in the form or short fiber.
After investigating the properties of asbestos tailings, it has been found that such tailings have excellent properties as filler for the manufacture of sheets or non-woven boards. It has to be understood that these asbestos tailings which are available in very large amounts of the appropriate granulometry still contain substantial amounts of short asbestos fiber to an extent that can be as high as 20%. Therefore, since asbestos fiber is well known for its excellent properties as an agent for sheet formation, it is not surprising that these tailings so rich in fiber also give good performances as inorganic filler, in the course of the formation of the sheet.
Notwithstanding the technical advantages of fibrous base felts incorporating asbestos fibers, it is believed that asbestos and asbestos-containing products possess carcinogenic properties with the consequence that many industries have, in recent years, either discontinued manufacturing and selling products incorporating asbestos fibers or have attempted to replace the asbestos fibers contained in said products by other less objectionable fibers or fillers, such as fiberglass, carbon fiber and mineral fiber such as rock wool.
Accordingly, because of the low cost of asbestos tailings of residues, it would appear highly desirable to use such tailings or residues as inert fillers in the manufacture of non-woven fibrous base felt material if the inherent disadvantages resulting from the presence of asbestos in said tailings could be eliminated.